Nuclear Developments in the Czech Republic

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iain
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Re: MSR group at Nuclear Research Insitute at Rez by Prague

Post by iain » Aug 17, 2009 8:23 pm

David wrote:I'll try contacting them shortly (something I should have done long ago...)
More than anything else, this is the most important thing we can do right now. We need the folks who are doing real work on MSRs to become familiar with what the other groups are doing, so that the funding path forward can become clear.

-Iain

badlooker
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Re: MSR group at Nuclear Research Insitute at Rez by Prague

Post by badlooker » Aug 18, 2009 1:15 am

Lars wrote: By the way, I think we could extract the 237Np instead of the 238Pu and recover 0.015 of the neutrons. This would assume that UF6 and NpF6 behave sufficiently differently that we could separate them by fractional distillation or similar method when we have them both as a gas in the fluorinator.
NpF6 and UF6 can not be separeted by distillition, becouse their boiling points are too close. NpF6 can be separated from UF6 by sorption on NaF or MgF2, but the efficiency is quite low ~ 60 - 70%.

J. Skarohlid

Lars
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Re: MSR group at Nuclear Research Insitute at Rez by Prague

Post by Lars » Aug 18, 2009 6:25 am

Welcome, we are glad to have you join us.

Thank you, I wasn't sure how hard it would be to separate Np from U.
It sounds like it is harder than I imagined.

David
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Re: MSR group at Nuclear Research Insitute at Rez by Prague

Post by David » Aug 18, 2009 8:55 am

badlooker wrote:
Lars wrote: By the way, I think we could extract the 237Np instead of the 238Pu and recover 0.015 of the neutrons. This would assume that UF6 and NpF6 behave sufficiently differently that we could separate them by fractional distillation or similar method when we have them both as a gas in the fluorinator.
NpF6 and UF6 can not be separeted by distillition, becouse their boiling points are too close. NpF6 can be separated from UF6 by sorption on NaF or MgF2, but the efficiency is quite low ~ 60 - 70%.

J. Skarohlid

Thanks, yes that was ORNL's method, using beds of NaF etc. I can't recall but I would imagine they simply used multiple beds to get around the modest efficiency. Since there was no rush to extract the NpF6 they could simply let it build up for quite awhile and then flush it out (simply by heating them I think?). Doesn't sound too expensive or hard at least on paper...

David L.

P.S. Just noticed your address is showing Rez, Czech Republic. Yes, a huge welcome, your group is certainly leading the way in many areas, especially in salt processing so any input you can share is appreciated. I hope we can also expand your views on new ways to implement Two Fluid designs (and many other interesting proposals).

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honzik
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Re: MSR group at Nuclear Research Insitute at Rez by Prague

Post by honzik » Aug 23, 2009 2:50 pm

David,

I have the same misgivings as you about this design. If one imagines the blanket salt system draining, the neutrons from the core are exposed to less absorptions from the blanket salt, but also some additional moderation from the graphite that lines the core.

I think, for safety's sake, it is important to bake into any design the loss of any salt system. I think the two fluid annular design can accomplish this, particularly if surrounding the outside of the pipes there is a material that acts as a neutron absorber. I'm guessing, (correct me if I'm wrong) that there will be an insignificant amount of diffusion of the neutrons to the absorber if the blanket salt is in the annulus. If the blanket salt were to drain, however, that would expose the absorber to greater flux, causing the reactor to go subcritical.

Also, I think the graphite issues - geometry changes that affect reactivity and the need for constant replacement - are problematic.

In short, the design has features that are worth studying, but I'm concerned that the apparent design goal of optimizing breeding has traded off against safety issues. This is something that is ultimately undesirable, particularly at the outset.

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ondrejch
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More pictures from Rez

Post by ondrejch » Oct 24, 2009 3:05 pm

Hi forum,
the next day (Aug 13 2009) I went to see the light water zero power reactor LR0 which is used for PWR core lattices neutronics experiments. The modular core allows for various other tests, including molten salts using special fuel bundles.
These pictures should have been posted earlier, I was swamped by work after returning to the US..
Attachments
p8130465.jpg
Fuel bundle for molten salt tests in LR0
p8130464.jpg
Fuel bundle for molten salt tests in LR-0
p8130462.jpg
Molten salt test loop from the Monicr alloy

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ondrejch
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Re: MSR group at Nuclear Research Insitute at Rez by Prague

Post by ondrejch » Oct 24, 2009 4:32 pm

more photos
Attachments
p8130467.jpg
The test fuel bundles are produced by Skoda Nuclear Engineering, and shipped in these boxes.
p8130463.jpg
VVER-1000 test fuel assembly, and me standing on top of the running reactor :)

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robert.hargraves
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Re: MSR group at Nuclear Research Insitute at Rez by Prague

Post by robert.hargraves » Dec 12, 2009 4:56 pm

Has anyone read or found a copy of

ICAPP09: Neutronic Analysis of Two-Fluid Thorium Molten Salt Reactor J. Frybort, R. Vocka

in which a two fluid reactor with a doubling time of 2.6 years is supposedly stated?

It was mentioned earlier in this thread, but I didn't see and answer and can't Google it.
Last edited by robert.hargraves on Dec 12, 2009 5:51 pm, edited 1 time in total.

Lars
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Re: MSR group at Nuclear Research Insitute at Rez by Prague

Post by Lars » Dec 12, 2009 5:46 pm

Is this something new? There was an earlier thread about a paper from this group. At this time the analysis was of startup conditions - no buildup of uranium above 233, no fission products, etc. When they finish the more complete analysis the doubling time will increase significantly.

For me, the most interesting part of this approach is that it seems like it would make for a very efficient device to convert u235 to u233.
Rather than manufacturing our startup fissile with a breeder we could mine it (as u235). Off-hand I'm thinking this will be noticeably less expensive.

Luke
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Re: MSR group at Nuclear Research Insitute at Rez by Prague

Post by Luke » Dec 12, 2009 6:44 pm

robert.hargraves wrote:Has anyone read or found a copy of

ICAPP09: Neutronic Analysis of Two-Fluid Thorium Molten Salt Reactor J. Frybort, R. Vocka

in which a two fluid reactor with a doubling time of 2.6 years is supposedly stated?

It was mentioned earlier in this thread, but I didn't see and answer and can't Google it.
A copy is attached to Ondrejch's 2nd comment on page 2 of this thread. It doesn't seem to be generally available.

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jaro
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Re: MSR group at Nuclear Research Insitute at Rez by Prague

Post by jaro » Oct 01, 2010 5:04 pm

Luke wrote:It seems Dr. Furukawa agrees with ondrech

IThEMS signs cooperation agreement with Czech MSR group.
That is excellent news !



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